Beginner Project: Build a Bluetooth Controlled Robot Car with Arduino

#include <SoftwareSerial.h>

// ———- Bluetooth ———-
SoftwareSerial BT(2, 3); // D2 = RX, D3 = TX for Bluetooth HC-05

// ———- Motor Driver Pins ———-
#define ENA 5 // Left motor speed (PWM)
#define IN1 7
#define IN2 8
#define ENB 6 // Right motor speed (PWM)
#define IN3 9
#define IN4 10

// ———- Variables ———-
int speedCar = 180; // Speed range: 0 – 255

// ———- Setup ———-
void setup() {
pinMode(ENA, OUTPUT);
pinMode(ENB, OUTPUT);
pinMode(IN1, OUTPUT);
pinMode(IN2, OUTPUT);
pinMode(IN3, OUTPUT);
pinMode(IN4, OUTPUT);

analogWrite(ENA, speedCar);
analogWrite(ENB, speedCar);

BT.begin(9600); // Default baud rate for HC-05
Serial.begin(9600); // Debugging
Serial.println(“Bluetooth Robot Ready!“);
}

// ———- Main Loop ———-
void loop() {
if (BT.available()) {
char command = BT.read();
Serial.println(command);

switch (command) {
case ‘F‘: forward(); break;
case ‘B‘: backward(); break;
case ‘L‘: leftTurn(); break;
case ‘R‘: rightTurn(); break;
case ‘S‘: stopCar(); break;

case ‘0‘ … ‘9‘: // Speed control
speedCar = map(command – ‘0’, 0, 9, 80, 255);
analogWrite(ENA, speedCar);
analogWrite(ENB, speedCar);
Serial.print(“Speed set to: “);
Serial.println(speedCar);
break;
}
}
}

// ———- Movement Functions ———-
void forward() {
digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}

void backward() {
digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}

void leftTurn() {
digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}

void rightTurn() {
digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}

void stopCar() {
digitalWrite(IN1, LOW); digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW); digitalWrite(IN4, LOW);
}